The present invention relates generally to dispensers for dispensing fluids or other substances and, more particularly, to a dispenser having a rigid vial, a flexible bladder disposed within the rigid vial and defining a chamber between the flexible bladder and rigid vial for receiving therein a fluid or other substance, and a nozzle and pump assembly coupled in fluid communication with chamber for dispensing fluids or other substances therefrom.
Typical fluid dispensers include a container defining therein a chamber for receiving a fluid to be dispensed, a nozzle and pump assembly mounted on the container, and a dip tube extending downwardly from the nozzle into the chamber for pumping the fluid from the bottom of the chamber, through the dip tube, and out of the dispenser. Other known dispensers include a vial and a flexible bladder received within the vial. For example, U.S. Pat. No. 6,062,430 to Fuchs shows in FIG. 1 a dispensing container with variable volume compensation including a bottle-shaped vessel 2 in the form of a thin-walled, hollow body made from soft elastic plastic, and a reception container 15 formed of a wrinkle film encapsulated within the vessel body 2.
One of the drawbacks associated with typical prior art fluid dispensers is that the fluid chamber(s) are not maintained in a substantially airless condition throughout the storage, shelf life and/or usage of the dispenser. For example, the nozzles and/or valves used in typical prior art dispensers frequently are incapable of maintaining the dispenser in a hermetically sealed condition. Such nozzles and/or valves allow the passage of air or other gases therethrough and into contact with the medicament or other substance contained within the fluid chamber(s). In addition, such nozzles and/or valves frequently allow vapor loss therethrough either during the storage, shelf life or usage of the dispensers.
Another drawback associated with prior art dispensers is that the materials of construction may undergo creep that, in turn, causes seals formed within the dispensers to leak. Many medicaments are maintained in storage and/or on store shelves for at least several, and in some instances, many months. During transportation and storage, the dispensers can be subjected to varying atmospheric conditions involving large variations in atmospheric temperature, pressure and/or humidity. As a result, the dispensers are frequently subjected to substantial differential thermal expansion and/or contraction that, in turn, cause the materials of construction to undergo creep. The seals and other components of such prior art dispensers typically are not designed to address such creep, and as a result, the dispensers develop leaks or otherwise allow air ingress and/or vapor loss when subjected to such long periods of storage or varying atmospheric conditions. For example, some polyethylene dispensers have been known to lose between about 10% to 25% of the weight of their contents during storage. Such weight loss is believed to be due to vapor loss from the medicament or other fluid-containing chambers through the polyethylene walls of the dispensers and/or through leaks otherwise created in the seals or other structural interfaces of the containers. The vapor loss is typically offset by air ingress into the chambers. Vapor loss and/or air ingress is particularly problematic for dispensers containing medicaments, such as pharmaceutical preparations or vaccines, because they tend to dilute each predetermined dosage of the medicament dispensed from the container, and/or cause the dispenser to dispense inconsistent concentrations of medicament from one dose to the next.
Yet another disadvantage associated with prior art dispensers is that because they cannot reliably maintain the medicament or other substance contained therein in an airtight condition, they cannot be used for either multiple dose applications or preservative-free formulations. The use of single dose dispensers can be substantially more expensive than multiple dose dispensers. In addition, the preservatives used in many medicaments, such as pharmaceutical preparations and vaccines, can cause adverse reactions in patients and/or dilute the effect of the medicament on the patient.
Another drawback of prior art dispensers is that the ullage or xe2x80x9cdead spacexe2x80x9d inherent in such dispensers allows sediment build-up. Many medicaments and other formulations contained within such dispensers are suspensions. The ullage or dead space in the prior art dispensers allows the solutes or other solid components of such suspensions to form sediment therein. Such settling of the suspensions dilutes the medicaments or other substances contained within the dispensers and, in turn, alters the medicament and/or the concentration of medicament in each patient dose.
Another drawback associated with many prior art dispensers is that they can only dispense the medicament or other substance contained therein in an upright or other single orientation. This drawback prevents such dispensers from being used effectively in other orientations, such as upside down. In addition, because such dispensers do not maintain the medicament or other substance contained therein in an airless condition, they cannot be used in low gravity environments, such as outer space.
Accordingly, it is an object of the present invention to overcome one or more of the above-described drawbacks and disadvantages of the prior art.
The present invention is directed to a dispenser for dispensing a fluid. The dispenser comprises a rigid housing, and a flexible bladder mounted within the housing and defining an interior chamber within the flexible bladder, and a fluid-receiving chamber between the flexible bladder and the rigid housing. The dispenser further comprises means for creating a first pressure within the fluid-receiving chamber greater than a second pressure within the interior chamber of the bladder to thereby prevent the ingress of gases or vapors into the fluid-receiving chamber. In a currently preferred embodiment of the present invention, the means for creating the pressure differential is formed by a resilient material of the bladder that flexes the bladder outwardly toward an expanded condition, and thereby creates the first pressure within the fluid-receiving chamber greater than the second pressure in the interior chamber of the bladder. Preferably, the resilient bladder is molded in the expanded condition, and therefore the resilient bladder will inherently tend to force itself into the expanded condition and thereby create the desired pressure differential between the fluid-receiving chamber and the interior chamber of the bladder.
A currently preferred embodiment of the dispenser further comprises a pump coupled in fluid communication with the fluid-receiving chamber for pumping a fluid received therein from the dispenser; and a one-way valve coupled in fluid communication with the pump for allowing the passage of the pumped fluid therethrough and preventing the passage of fluids in the opposite direction. The one-way valve is preferably formed by a nozzle, and a flexible cover overlying the nozzle and creating the one-way valve at the interface of the nozzle and cover.
The preferred dispenser of the present invention further comprises a seal formed between the flexible bladder and the rigid vial for sealing the fluid-receiving chamber. The seal includes a first protuberance extending radially outwardly on an outer surface of the flexible bladder, and a second protuberance axially spaced relative to the first protuberance and extending radially inwardly on an inner surface of the bladder. The first and second protuberances are subject to radial compression to seal the interface between the flexible bladder and rigid vial. Preferably, the first protuberance extends about an outer peripheral surface of the bladder and defines an outer annular sealing surface, and the second protuberance extends about an inner peripheral surface of the bladder and defines an inner annular sealing surface. In addition, the first protuberance defines a tapered surface for directing bladder material in approximately the direction of the second protuberance to thereby facilitate maintaining a fluid-tight seal in the event of bladder material creep. The seal preferably further includes a peripheral flange extending about an open end of the flexible bladder and subject to axial compression for further sealing the interface between the bladder and rigid vial.
The dispenser of the present invention further comprises a plug receivable within an open end of the rigid vial and engageable with at least one of the first and second protuberances for radially compressing the protuberances to seal the interface between the flexible bladder and rigid vial. The plug defines at least one aperture therethrough in fluid communication with the interior chamber of the flexible bladder. Preferably, a two-way valve of the dispenser is coupled in fluid communication between the interior chamber of the flexible bladder and the aperture of the plug for preventing fluid communication between the interior chamber of the bladder and the ambient atmosphere when a pressure differential across the two-way valve is less than a threshold level. The two-way valve preferably is formed by a flexible, annular protuberance extending radially inwardly from an inner peripheral surface of the flexible bladder, and engageable with an annular surface of the plug to thereby seal the interface between the flexible bladder and plug. In a currently preferred embodiment of the present invention, the annular protuberance defines axially-opposed surfaces that taper inwardly in the radial direction to facilitate flexing of the protuberance in response to the pressure differential across the protuberance exceeding the predetermined threshold level.
The flexible bladder of the dispenser further defines an open end and a closed end, and is movable between a collapsed condition and an expanded condition. Upon expansion of the flexible bladder from the collapsed condition into the expanded condition, the flexible bladder and rigid vial define an annular gap therebetween. In a currently preferred embodiment, the annular gap defines an increasing width in the axial direction from the open end toward the closed end of the flexible bladder, to facilitate removal of fluid from the fluid-receiving chamber upon expansion of the bladder. Preferably, the flexible bladder initially contacts the rigid vial adjacent to or near the open end of the bladder, and then progressively engages the rigid vial in the axial direction from the open end toward the closed end of the flexible bladder with further expansion thereof. Also in accordance with a preferred embodiment of the dispenser, the flexible bladder defines an external morphology in an expanded condition, the rigid vial defines an internal morphology, and the external and internal morphologies are substantially the same to thereby allow the flexible bladder to conformably contact the rigid vial and substantially eliminate any dead space in the fluid-receiving chamber therebetween.
In accordance with a preferred embodiment of the present invention, the pump of the dispenser comprises a piston, and a slide for slidably receiving the piston therein. At least one of the piston and the slide is reciprocable relative to the other. In addition, the piston is made of a relatively hard material, the slide is made of a relatively soft material, and the piston causes a compression zone of the slide to flex outwardly upon moving at least one of the piston and the slide relative to the other to thereby effect a fluid-tight seal between the piston and slide. In addition, forming the slide from a relatively flexible material allows the slide to be formed integral with a nozzle, such as by molding the two components in a single part, wherein the integral nozzle and slide may be released from a core pin by injecting pressured air therebetween.
The dispenser of the present invention preferably further comprises means for controlling the flexible bladder to collapse into a predetermined collapsed condition. In one embodiment of the present invention, the means for controlling includes a plurality of legs extending axially inwardly into the interior chamber of the flexible bladder for conformably contacting the flexible bladder upon collapse thereof. In another embodiment of the present invention, the means for controlling is defined by at least one axially elongated surface discontinuity formed in the flexible bladder.
In accordance with another embodiment of the present invention, the flexible bladder is capable of being penetrated by a needle or like injection member for introducing a predetermined substance into the fluid-receiving chamber. In this embodiment, the flexible bladder includes a first portion substantially infusible in response to the application of thermal energy thereto and compatible with the substance to be received within the fluid-receiving chamber, and a second portion overlying the first portion and fusible in response to the application of thermal energy thereto. Thus, the second portion enables the formation of a substantially fluid-tight seal between the flexible bladder and fluid-receiving chamber in a region thereof penetrated by the needle or like injection member. In one embodiment of the present invention, the second portion is formed of either a thermoplastic or an elastomeric material, and the bladder, including the first portion thereof, is formed of vulcanized rubber.
One advantage of the dispenser of the present invention is that the pressure differential between the fluid-receiving chamber and the internal chamber of the bladder and ambient atmosphere substantially prevents the ingress of air or other gases or vapors through the flexible bladder, or otherwise into the fluid-receiving chamber. As a result, the dispensers of the present invention may maintain the medicaments or other substances contained therein in an airless condition throughout substantial periods of storage, shelf life and/or use. Accordingly, the dispensers of the present invention are particularly well suited for dispensing multiple doses of non-preserved medicaments or other substances requiring storage in an airless condition.
Another advantage of the dispensers of the present invention is that the seal formed between the flexible bladder and the rigid vial radially and axially directs the material of the flexible bladder to persistently maintain a fluid-tight seal regardless of any creep of the material during the storage or shelf-life of the dispenser. In addition, the one-way valve employed in the preferred embodiments of the present invention further maintains the fluid-receiving chamber in a hermetically-sealed condition throughout the storage, shelf-life and/or use of the dispenser.
Yet another advantage of the dispensers of the present invention is that because the medicament or other substance is maintained in an airless condition in the fluid-receiving chamber, the dispensers may be used in virtually any orientation, and furthermore, may be used in low gravity environments.
Another advantage of the dispensers of the present invention is that the flexible bladder preferably defines an external morphology substantially matching the internal morphology of the rigid vial. As a result, the flexible bladder may expand and conformably contact the rigid vial throughout the interface between these two parts and, in turn, eliminate any dead space within the fluid-receiving chamber.
Yet another advantage of the dispensers of the present invention is that the two-way valve coupled in fluid communication between the interior chamber of the flexible bladder and the ambient atmosphere prevents any exchange of gases or vapors between the interior chamber of the bladder and ambient atmosphere, provided the pressure differential across the valve is less than a predetermined level. As a result, the two-way valve creates a relatively stable micro-atmosphere within the interior chamber of the flexible bladder, thus insulating the interior chamber from fluctuations in pressure and/or humidity in the ambient atmosphere and thereby further preventing the ingress of gas or vapors into the fluid-receiving chamber.
Other objects and advantages of the present invention will become apparent in view of the following detailed description and accompanying drawings.